GFAP-positive-astroglia.jpg

While neurons mainly relay or process information throughout the nervous system, there are numerous types of glia fulfilling roles that have only recently been . In general, glia play a vital supporting role for neurons and are crucial for their survival. Glia can be divided into microglia and macroglia. Microglia are distributed throughout the CNS, constantly surveying the neuronal environment and performing immune functions to eliminate foreign material as well as remove dead neurons. The macroglia include astrocytes, Schwann cells and oligodendrocytes. Astrocytes provide nutrients for neurons, integrate neuronal inputs and regulate the neuronal environment around synapses. They are primarily involved in monitoring synaptic activity and can modulate neurotransmission by removing or secreting neurotransmitters in the synaptic cleft [1] . Schwann cells and oligodendrocytes myelinate axons in the peripheral (PNS) and central nervous systems (CNS) respectively to enhance conduction velocity. In the case of axonal damage in the CNS, axons are unable to regenerate because of the presence of oligodendroglia, which may release molecules that inhibit axonal regrowth [2] . In the absence of oligodendroglia in the PNS, it is possible for peripheral nerves to regenerate axons. Axons in the PNS are surrounded by Schwann cells, which produce and recruit factors that encourage axonal regeneration [3] . The process of axonal regeneration in the PNS involves transcription factors, degradation of the myelin sheath, and reinnervation of the nerves. Understanding these complex glial-neural interactions may guide treatment of brain trauma and other neurodegenerative diseases.






Contents

1. Modulation of Synapses (Amy Chow)
  1. The Tripartite Synapse
  2. Clearance of Neurotransmitters from the Synaptic Cleft
  3. Sensing Synaptic Activity
  4. Secretion of Gliotransmitters into the Synaptic Cleft
    A. Role of Adenosine in Sleep and Sleep Deprivation
  5. Controversy over Gliotransmitters Modulating Synaptic Activity In Vivo

illus_cim13_page_10_350.jpg

2. Nerve Regeneration in the Peripheral Nervous System (Lydia Yeung)
2.1 Degeneration and Demyelination of the Axon
2.1.a Dedifferentiation of Schwann Cells
2.1.b Removal of Debris
2.2 Regeneration of Axon
2.2a Schwann Cells Guide Axons Back to Target Tissue
2.2b Redifferentiation of Schwann Cells
2.3 Clinical Applications of PNS Regeneration






References: </references>
  1. ^
    Shaham, S. Glia-neuron interactions in nervous system function and development. Current topics in developmental biology 69, 39-66 (2005).
  2. ^ Bear, Mark F., Conners, Barry W., Paradiso, Michael A. Neuroscience: Exploring the Brain. Lippincott Williams & Wilkins, Baltimore, 3rd edition (2007).
  3. ^ Ferguson, T. A., Son, Y. J., Extrinsic and intrinsic determinants of nerve regeneration. Journal of tissue engineering (2011) Sept 13 - Epub